Calorie Calculator

A calorie calculator estimates the number of calories your body needs each day based on your age, sex, height, weight, and physical activity level. Understanding your daily calorie needs is the foundation of effective weight management, athletic performance, and long-term health — whether you're in the United States, Canada, or anywhere else.

What Is a Calorie?

A calorie (kcal) is a unit of energy. In nutrition, it refers to the amount of energy provided by food and beverages. Your body uses this energy to fuel every biological process — from breathing and circulation to exercise and digestion. One kilocalorie equals 4.184 kilojoules (kJ), the unit used in some countries including Canada on nutrition labels.

BMR — Basal Metabolic Rate

Your Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest to sustain vital functions — breathing, circulation, body temperature, and cell repair. BMR represents the minimum caloric floor: even if you stayed in bed all day, your body would still burn this many calories.

Mifflin-St Jeor Formula

Developed in 1990, the Mifflin-St Jeor equation is widely considered the most accurate BMR formula for the general population. It is the default formula used in this calculator and recommended by the Academy of Nutrition and Dietetics.

• Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
• Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Revised Harris-Benedict Formula

The original Harris-Benedict equation (1919) was revised in 1984 to improve accuracy. It remains widely used and produces results similar to Mifflin-St Jeor for most people.

• Men: BMR = 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age)
• Women: BMR = 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)

Katch-McArdle Formula

The Katch-McArdle formula calculates BMR from lean body mass — the weight of everything in your body except fat. It requires knowing your body fat percentage, making it more precise for athletes and individuals with higher-than-average muscle mass.

• Lean Body Mass (LBM): LBM = weight (kg) × (1 − body fat % ÷ 100)
• BMR: 370 + (21.6 × LBM in kg)

Because it accounts for muscle mass, Katch-McArdle often produces higher BMR estimates for lean, muscular individuals and lower estimates for those with higher body fat — making it the most individualised of the three formulas.

TDEE — Total Daily Energy Expenditure

TDEE is your total daily calorie burn including all physical activity. It is calculated by multiplying your BMR by an activity factor, also called the Physical Activity Level (PAL).

Activity Levels and Multipliers

• Sedentary (×1.2): Desk job, little or no intentional exercise
• Light (×1.375): Light exercise or sport 1–3 days per week
• Moderate (×1.55): Moderate exercise or sport 4–5 days per week
• Active (×1.725): Hard exercise or sport 6–7 days per week
• Very Active (×1.9): Hard daily training plus a physically demanding job

Your TDEE is the number of calories you need to maintain your current weight. Eating below your TDEE creates a calorie deficit (leading to fat loss); eating above it creates a surplus (leading to weight gain).

Caloric Goals

Weight Loss

A deficit of approximately 500 kcal per day results in a loss of roughly 0.5 kg (1.1 lb) per week. A deficit of 1,000 kcal per day produces about 1 kg (2.2 lb) per week. Deficits larger than this are generally not recommended without medical supervision as they risk muscle loss, nutrient deficiencies, and metabolic adaptation.

Weight Gain

A surplus of 500 kcal per day results in approximately 0.5 kg (1.1 lb) of weight gain per week. For lean muscle gain, a smaller surplus of 200–300 kcal paired with resistance training is often recommended to minimise fat gain.

Maintaining Weight

Eating at your TDEE maintains your current weight. Small fluctuations day-to-day are normal due to water retention, glycogen stores, and the weight of food in the digestive system.

Macronutrients

Calories come from three macronutrients: protein (4 kcal/g), carbohydrates (4 kcal/g), and fat (9 kcal/g). Alcohol also provides energy at 7 kcal/g but has no nutritional value.

Protein

Protein is essential for building and repairing muscle tissue, producing enzymes and hormones, and maintaining satiety. General recommendations range from 0.8 g per kg of body weight (minimum for sedentary adults) to 1.6–2.2 g/kg for active individuals and athletes.

Fats

Dietary fat supports hormone production, absorption of fat-soluble vitamins (A, D, E, K), and brain function. Most guidelines recommend 20–35% of total daily calories from fat, with an emphasis on unsaturated sources such as olive oil, nuts, avocado, and fatty fish.

Carbohydrates

Carbohydrates are the body's preferred energy source, especially during high-intensity exercise. Complex carbohydrates from whole grains, legumes, vegetables, and fruit provide sustained energy and dietary fibre. The remaining calories after protein and fat targets are met are typically allocated to carbohydrates.

Calories in Canada vs the United States

The calorie needs of Canadians and Americans are calculated using the same physiological formulas — energy expenditure is determined by biology, not geography. However, there are some practical differences worth knowing:

• Nutrition labels: Canada displays energy in both Calories (kcal) and kilojoules (kJ) on food packaging, while the US uses Calories (kcal) only.
• Dietary guidelines: Health Canada's food guide and the USDA Dietary Guidelines both recommend similar macronutrient distributions but differ in specific food group recommendations.
• Reference Daily Intakes: Canada uses 2,000 kcal as the daily reference value on Nutrition Facts tables, the same as in the US.

This calculator supports both kcal and kJ output and works equally for users in the United States and Canada.